The present invention relates to a punch tool such as is used, for example, in a foil processing plant, for trimming the edge of a coated continuous foil.
Punch tools that are being moved are occasionally used in foil processing plants. The foil material that is provided in the form of a web is continuously advanced in a material advance direction. The punch tool comprises an upper tool and a lower tool, whereby the upper tool is arranged above the foil material and the lower tool is arranged below the foil material. In order to perform the punching operation, the closing punch tool is moved synchronously with the movement of the foil material with said foil material. After the punching stroke has been completed, the punch tool opens and is then again moved back into the home position. Consequently, the punch tool performs not only an opening and closing movement but, in addition, a back and forth movement in and against the foil transport direction or against the workpiece transport direction. In each instance, the punching unit moves for the duration of a punching operation with the passing foil. Thereafter, the punch tool returns in opened state into its original position in order to machine the next foil section.
Inasmuch as the punch tool is mounted to a support and is not rigidly connected to the machine frame but, rather, performs a continuous forward and reverse movement, the acceleration forces act on the punch stamp and the cutting plate, which may lead to inaccuracy problems. If thin and sensitive foils are to be punched and/or if particularly high demands are made on the accuracy of the punch cuts to be performed or on their quality, it can become difficult to ensure the required precision of the punching operation.
It is an object to remedy this and state measures by which, in particular in movably supported punch tools, high accuracy requirements can be met.